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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package javax.swing;

import javax.swing.event.*;
import java.io.Serializable;
import java.util.EventListener;

/**
 * The abstract definition for the data model that provides
 * a <code>List</code> with its contents.
 * <p>
 * <strong>Warning:</strong>
 * Serialized objects of this class will not be compatible with
 * future Swing releases. The current serialization support is
 * appropriate for short term storage or RMI between applications running
 * the same version of Swing.  As of 1.4, support for long term storage
 * of all JavaBeans&trade;
 * has been added to the <code>java.beans</code> package.
 * Please see {@link java.beans.XMLEncoder}.
 *
 * @param <E> the type of the elements of this model
 * @author Hans Muller
 */
public abstract class AbstractListModel<E> implements ListModel<E>, Serializable {

  protected EventListenerList listenerList = new EventListenerList();


  /**
   * Adds a listener to the list that's notified each time a change
   * to the data model occurs.
   *
   * @param l the <code>ListDataListener</code> to be added
   */
  public void addListDataListener(ListDataListener l) {
    listenerList.add(ListDataListener.class, l);
  }


  /**
   * Removes a listener from the list that's notified each time a
   * change to the data model occurs.
   *
   * @param l the <code>ListDataListener</code> to be removed
   */
  public void removeListDataListener(ListDataListener l) {
    listenerList.remove(ListDataListener.class, l);
  }


  /**
   * Returns an array of all the list data listeners
   * registered on this <code>AbstractListModel</code>.
   *
   * @return all of this model's <code>ListDataListener</code>s, or an empty array if no list data
   * listeners are currently registered
   * @see #addListDataListener
   * @see #removeListDataListener
   * @since 1.4
   */
  public ListDataListener[] getListDataListeners() {
    return listenerList.getListeners(ListDataListener.class);
  }


  /**
   * <code>AbstractListModel</code> subclasses must call this method
   * <b>after</b>
   * one or more elements of the list change.  The changed elements
   * are specified by the closed interval index0, index1 -- the endpoints
   * are included.  Note that
   * index0 need not be less than or equal to index1.
   *
   * @param source the <code>ListModel</code> that changed, typically "this"
   * @param index0 one end of the new interval
   * @param index1 the other end of the new interval
   * @see EventListenerList
   * @see DefaultListModel
   */
  protected void fireContentsChanged(Object source, int index0, int index1) {
    Object[] listeners = listenerList.getListenerList();
    ListDataEvent e = null;

    for (int i = listeners.length - 2; i >= 0; i -= 2) {
      if (listeners[i] == ListDataListener.class) {
        if (e == null) {
          e = new ListDataEvent(source, ListDataEvent.CONTENTS_CHANGED, index0, index1);
        }
        ((ListDataListener) listeners[i + 1]).contentsChanged(e);
      }
    }
  }


  /**
   * <code>AbstractListModel</code> subclasses must call this method
   * <b>after</b>
   * one or more elements are added to the model.  The new elements
   * are specified by a closed interval index0, index1 -- the enpoints
   * are included.  Note that
   * index0 need not be less than or equal to index1.
   *
   * @param source the <code>ListModel</code> that changed, typically "this"
   * @param index0 one end of the new interval
   * @param index1 the other end of the new interval
   * @see EventListenerList
   * @see DefaultListModel
   */
  protected void fireIntervalAdded(Object source, int index0, int index1) {
    Object[] listeners = listenerList.getListenerList();
    ListDataEvent e = null;

    for (int i = listeners.length - 2; i >= 0; i -= 2) {
      if (listeners[i] == ListDataListener.class) {
        if (e == null) {
          e = new ListDataEvent(source, ListDataEvent.INTERVAL_ADDED, index0, index1);
        }
        ((ListDataListener) listeners[i + 1]).intervalAdded(e);
      }
    }
  }


  /**
   * <code>AbstractListModel</code> subclasses must call this method
   * <b>after</b> one or more elements are removed from the model.
   * <code>index0</code> and <code>index1</code> are the end points
   * of the interval that's been removed.  Note that <code>index0</code>
   * need not be less than or equal to <code>index1</code>.
   *
   * @param source the <code>ListModel</code> that changed, typically "this"
   * @param index0 one end of the removed interval, including <code>index0</code>
   * @param index1 the other end of the removed interval, including <code>index1</code>
   * @see EventListenerList
   * @see DefaultListModel
   */
  protected void fireIntervalRemoved(Object source, int index0, int index1) {
    Object[] listeners = listenerList.getListenerList();
    ListDataEvent e = null;

    for (int i = listeners.length - 2; i >= 0; i -= 2) {
      if (listeners[i] == ListDataListener.class) {
        if (e == null) {
          e = new ListDataEvent(source, ListDataEvent.INTERVAL_REMOVED, index0, index1);
        }
        ((ListDataListener) listeners[i + 1]).intervalRemoved(e);
      }
    }
  }

  /**
   * Returns an array of all the objects currently registered as <code><em>Foo</em>Listener</code>s
   * upon this model. <code><em>Foo</em>Listener</code>s are registered using the
   * <code>add<em>Foo</em>Listener</code> method. <p> You can specify the <code>listenerType</code>
   * argument with a class literal, such as <code><em>Foo</em>Listener.class</code>. For example,
   * you can query a list model <code>m</code> for its list data listeners with the following code:
   *
   * <pre>ListDataListener[] ldls = (ListDataListener[])(m.getListeners(ListDataListener.class));</pre>
   *
   * If no such listeners exist, this method returns an empty array.
   *
   * @param listenerType the type of listeners requested; this parameter should specify an interface
   * that descends from <code>java.util.EventListener</code>
   * @return an array of all objects registered as <code><em>Foo</em>Listener</code>s on this model,
   * or an empty array if no such listeners have been added
   * @throws ClassCastException if <code>listenerType</code> doesn't specify a class or interface
   * that implements <code>java.util.EventListener</code>
   * @see #getListDataListeners
   * @since 1.3
   */
  public <T extends EventListener> T[] getListeners(Class<T> listenerType) {
    return listenerList.getListeners(listenerType);
  }
}
